COLORECTAL-CARCINOMA IN DIFFERENT AGE-GROUPS - A POPULATION-BASED INVESTIGATION

Although colorectal cancer is a disease of the older population, these tumors are not infrequent before the age of 55. Through the data of a population-based registry, we proposed giving a description of the cl inical features of three groups of patients in whom the disease occurr ed at a relatively early age of onset (group I: < 40 yr; group II: 41- 50 yr; group III: 51-55 yr). There were only 14 patients under the age of 40 yr (1.1% of total registered patients, n = 1298 in the period 1 984-1992). Group II and III represented 5.9% and 6.0%, respectively (n = 76 and 78), with minor fluctuations throughout the 9-yr period of r egistration. Inherited colorectal tumors [hereditary nonpolyposis colo rectal cancer (HNPCC), adenomatosis coli, and suspected HNPCC] account ed for 38.4% of group I patients (5 of 14), 17.1% of group II, 10.2% o f group III, and only 3.5% of individuals older than 55 (p, for trend, < 0.001). Thus, hereditary colorectal tumors were detected significan tly more often in younger individuals. The majority of colorectal mali gnancies were localized in the left colon or rectum in all three group s,,vith a tendency (not significant) to a preferential localization in the right colon for tumors developed in group I (37% vs 18% and 14% i n groups II and III, respectively). Pathological stage and main histol ogical types did not differ among the three groups. Finally, life-tabl e analysis did not show significant differences in 5-yr survival among the three groups; however, when considered together, early onset case s showed a more favorable prognosis than older individuals (log-rank 1 1.6; p < 0.001). In conclusion, colorectal cancer is diagnosed very ra rely before the age of 40 yr, whereas about 12% of all cases belong to the age group 41 to 55 yr of age. Hereditary tumors were found more f requently in younger patients, with a well-defined inverse relationshi p between age of onset and frequency of genetically determined tumors. Finally, the clinical outcome was more favorable in the whole series of early onset cases than in older registered patients.